Cutting device

ABSTRACT

The invention relates to a cutting device comprising a holder ( 10 ), which is provided with a jaw-like opening ( 24 ) on a clamping head ( 20 ) that serves to accommodate a metal-cutting tool ( 22 ). The jaw-like opening ( 24 ) is located on a longitudinal side ( 16 ) of the clamping head ( 20 ) and its face ( 28 ) extending transversal to said longitudinal side ( 16 ) faces a workpiece ( 30 ) that rotates during metal-cutting machining. The face ( 28 ) is provided, at least in the area in which it leads into the opening ( 24 ), with a camber ( 32 ) whose curvature corresponds to the curvature of the workpiece ( 30 ) having the largest diameter.

[0001] The invention relates to a cutting device with a holder which is provided on the clamping head for holding a metal-cutting tool with a jaw-like receptacle that is located on one longitudinal side of a clamping head, with a front face which runs transversely to its longitudinal side facing the workpiece which rotates during metal-cutting machining.

[0002] These cutting devices (U.S. Pat. No. 5,267,817 A, WO 99/50 012) are obtainable in a plurality of embodiments of the prior art and are freely available on the market. The known approaches are used especially for end-cut turning and plain turning and for cut-off operations on a rotating workpiece which is made generally rotationally symmetrical as a turned part. The known cutting devices have an elongated holder with a square cross section which can be fixed over the area of its one free end on a tool holder, and several cutting devices can be held in a holder device, often under constricted installation conditions. The cutting devices can be located horizontally in a row on top of one another in the overall holder device, but also directly next to one another. On its other end the holder undergoes transition in one piece into a block-like clamping head which holds the metal-cutting tool on its side by way of a receptacle. This block-like clamping head has essentially plane surfaces to all sides which transition into one another at a right angle. In particular the front face of the clamping head is made in the form of a straight plane which runs at a right angle to the bottoms and tops and the longitudinal sides of the holder. The metal-cutting tool with its machining cutting edge projects from this flat plane forward in the direction of the machining zone and with respect to the indicated geometrical structure of the clamping head, the cutting edge of the machining tool on the rotating workpiece must first create a clear space so that for deeper machining the clamping head can follow over its entire width. In particular, in a constricted installation situation for the cutting device and for cramped machining areas on the rotating workpiece into which for example only a thin machining groove is to be made the known approaches are unsuitable, since in these instances the rotating workpiece would then collide with the front face of the clamping head.

[0003] On the basis of this state of the art, the object of the invention is to further improve a cutting device of the initially mentioned type such that it can be easily used even under constricted installation conditions and that it is possible with it to cut even narrow geometries into the workpiece at a definable depth without collisions between the machining tool and the workpiece. The pertinent object is achieved by a cutting device with the features of claim 1.

[0004] In that as specified in the characterizing part of claim 1, the front face is provided, at least in the area where it leads into the receptacle, with a camber whose curvature corresponds to the curvature of the workpiece with the largest diameter for which the cutting device is intended as a machining tool, the front face of the clamping head which is cambered at least in parts recedes relative to the workpiece to be machined and the machining tool conversely projects distinctly in the manner of a retaining rib held in the direction of the machining tool so that depending only on the width of the cutting edge which can be engaged can a geometry be defined in the rotating tool, for example in the form of a recessed groove which runs narrowly especially in cross section or the like. The cambered front face forms a space in which the rotating workpiece can move so that basically the clamping head during machining holds parts of the tool and in this way makes it possible for the machining tool to have a high penetration depth without, as in the known approaches, the clamping head first having to follow in the space of the rotating tool which is to be machined clear.

[0005] In one preferred embodiment of the cutting device as claimed in the invention, the receptacle is part of the retaining rib which projects as an integral component of the clamping head from the latter, the camber of the front face extending from the area of the receptacle to the bottom of the clamping head. As a result of this retaining rib, a stiffened overall structure is still obtained in the area of the clamping head and the forces that occur during machining can be diverted reliably from the cutting edge of the machining tool by way of said machining tool into the retaining rib and thus into the remaining clamping head.

[0006] In another preferred embodiment of the cutting device as claimed in the invention, the camber of the front face on the top of the clamping head undergoes transition into an obliquely running flattened area which is penetrated by a setscrew that changes the clear cross section of the clamping gap which passes at least through the clamping head and which leads into the receptacle. If there are several holders on the cutting device in a central holder receptacle of a machine tool or the like directly in a horizontal plane next to one another, it is possible to replace a machine tool when it is worn by a new one by way of the setscrew which is accessible from overhead without including the remaining holder configuration in the replacement process. Thus the replacement process can be undertaken quickly and with precision entailing low installation effort; this greatly reduces downtimes.

[0007] In another preferred embodiment of the cutting device as claimed in the invention, the clamping gap in the area of its longitudinal side facing away from the receptacle is penetrated at least partially by a bearing block site. The bearing block site in question ensures that the clamping process for the machining tool is not undertaken on one side; this would possibly lead to tilting which would ultimately adversely affect the machining precision. Rather the bearing block site ensures that the clamping gap is uniformly reduced so that in the fixing process of the tool on the retaining rib no tilting can occur.

[0008] In another preferred embodiment of the cutting device as claimed in the invention the cambered front face on the bottom of the clamping head undergoes transition into a support surface which extends obliquely to the feed direction of the tool from the receptacle in the direction of the clamping head. The material use for the clamping head is further reduced by way of the pertinent oblique support surface and yet the overall construction of the clamping head is stiffened by way of the support surface such that machining precision is not adversely affected. Since as a result of the support surface, material in the area of the front face of the clamping head can be saved, additional space is consequently created in the area of the clamping head which can be used by the rotating workpiece in machining without the danger of collisions.

[0009] In one especially preferred embodiment of the cutting device as claimed in the invention, the distance between the cambered front face of the clamping head and the machining cutting edge of the metal-cutting tool is slightly larger than the largest possible diameter of the rotating workpiece which is designed for machining with this tool. Thus it is possible to carry out a cut-off process on a workpiece along a groove path with a narrow structure without collisions occurring. Then a larger clear space on the workpiece need no longer be formed first by way of the tool, as was necessary in the prior art, in order to then be able to undertake the cut-off process in several steps. Rather the cut-off process is possible with a feed motion.

[0010] Other advantageous embodiments are the subject matter of the other dependent claims.

[0011] The cutting device claimed for the invention is described in greater detail in what follows on the basis of various embodiments as shown in the drawings in different views. The following figures are in diagram form and are not drawn to scale.

[0012] FIGS. 1 to 3 show a first embodiment of the cutting device;

[0013]FIGS. 4, 5, and 6 show a second embodiment, and

[0014]FIGS. 6 and 7 show a third embodiment.

[0015] As shown in FIG. 1, the cutting device has a holder 10 with an essentially square cross section. Viewed in the line of sight to FIG. 1, the holder 10 has a top 12, a bottom 14 and viewed in the machining direction a left and a right longitudinal side 16 and 18. The shaft part of the holder 10 is made relatively long in order to form a large contact surface for the holder receptacle (not shown) of a machine tool such as a lathe (not shown) or the like. On its front end the holder 10 is provided with a clamping head 20. The block-like clamping head 20 undergoes transition with its side surfaces except for its front face flush into the side surfaces of the holder 10 and projects only in the area of the top of the holder 10 with a definable projection. For holding a metal-cutting tool 22 the clamping head 20 is provided with a jaw-like receptacle 24 which in the embodiment shown is located on the left longitudinal side 16 of the clamping head 20. The metal-cutting tool 22 forms essentially a hard metal cutting tool with two diametrically opposite machining cutting edges 26. In the drawings only the machining cutting edge 26 which is intended for machining is shown and it can be released when worn by opening the jaw-like receptacle 24 of the metal cutting tool 22. After turning the metal-cutting tool 22 by 180° around its transverse axis, the new machining cutting edge 26 can then be engaged to the workpiece by the metal-cutting tool 22 then being fixed by way of the clamp receptacle 24 again on the clamping head 20 of the holder 10 in another step. Pertinent replacement is conventional so that it will not be detailed here.

[0016] Transversely to the longitudinal sides 16 and 18 of the holder 10, the clamping head 20 has a front face 28 which is facing a rotating workpiece 30 (turned part) in a metal-cutting machining process. The workpiece 30 shown in FIG. 3 is to be machined with the cutting device, for example it is to be exposed from the outside to a cut-off turning or a plain turning process. Furthermore, it should be possible to carry out a cut-off process with the cutting device, in which the machining cutting edge 26, as shown in FIG. 3, penetrates as far as the longitudinal axis or the center of rotation of the workpiece 30 in order to cut parts of the workpiece off the workpiece 30 which remains in the chuck or the like on the machine. For the following description, the workpiece 30 should have a machining diameter of a maximum of 20 mm. Depending on how the machining geometries are chosen here, the cutting device with its geometrical dimensions can then be matched according to the machining situation. As is to be understood from FIG. 3, in the machining situation shown there, in which the machining cutting edge 26 has reached the middle of the workpiece 30, the bottom 14 of the holder 10 extends as far as the effective edge of the machining cutting edge 26 over the radius of the turned part or the workpiece 30; this corresponds to the engagement height of half of the machining diameter, i.e., 10 mm.

[0017] As is apparent from FIGS. 1 to 3, and especially from FIG. 2, the front face 28 at least in the area in which it is undergoes transition into the receptacle 24 is provided with a camber 32 whose curvature corresponds to the curvature of the workpiece 30 with the largest diameter, here 20 mm, for which the cutting device is intended as a metal-cutting tool 22.

[0018] The receptacle 24 is part of a retaining rib 34 of the clamping head 20. The pertinent retaining rib 34 in an extension of the left side 16 of the holder 10 consequently is an integral component of the clamping head 20. Furthermore, the camber 32 of the front face 28 on the top 12 of the clamping head 20 undergoes transition into an obliquely running flattened area 36 in the manner of a side surface which is penetrated by a setscrew 38 which changes the clear cross section of the clamping gap 40 which penetrates at least the clamping head 20 and which ends in a bent curve with its one side in the area of the holder 10 and with its other area communicates to the exterior, on the cambered front face 28. When the setscrew 38 is loosened, the clamping gap 40 is cleared and due to the inherent elasticity of the material parts of the clamping head 20 the jaw-like receptacle 24 gapes somewhat apart and releases the metal-cutting tool 22 for replacement. In this way the metal-cutting tool 22 can be fixed again in the jaw-like clamp receptacle 24 in the reverse sequence.

[0019] As follows furthermore from FIG. 3, the distance between the cambered front face 28 of the clamping head 20 and the machining cutting edge 26 of the metal-cutting tool 22 is slightly larger than the largest possible diameter (20 mm) of the rotating workpiece 30 which is intended for machining with this metal-cutting tool 22. Thus in the clamping head 20 a clear space is formed which the rotating workpiece parts 30 can enter without a collision occurring between the clamping head 20 of the holder 10 and the workpiece 30 in machining with the metal-cutting tool 22. In this way great machining depths on the workpiece 30 can be attained, as can groove geometries with an exceptionally narrow structure without space having to be formed first for this on the workpiece 30 by metal cutting for penetration of the clamping head 20 with the metal cutting tool 22.

[0020] As can be seen from FIG. 2, the clamping gap 40 in the area of its longitudinal side (right side 18) facing away from the receptacle 24 is penetrated at least partially by a bearing block site 42 which fits like a pin into the recess 44 in the clamping head 20. If the setscrew 38 is tightened for a fixing process, the upper wall of the clamping gap 40 can accordingly be supported on the bearing block site 42 and the clamping process takes place over the entire width of the metal-cutting tool 22 by way of the retaining rib 34, tilting cannot occur; this could adversely affect machining precision. The clamping gap 40 which projects over the clamping head 20 in the direction of the holder 10 into the latter thus is provided with additional support.

[0021] Furthermore, the cambered front face 28 on the bottom 14 of the clamping head 20 undergoes transition into a support surface 46 which extends obliquely to the feed direction of the metal-cutting tool 22 from the receptacle 24 in the direction of the clamping head 20. The pertinent support surface 46 in turn saves material on the clamping head 20; this reduces the danger of collisions with the workpiece 30 which is to be machined. In spite of the pertinent material saved, the retaining rib 34 is stiffened by way of the support surface 46 and the cambered front face 29 with the result that in spite of the low material use for the clamping head 20 the metal-cutting machine tool 22 is reliably fixed in its holder 24 so that the cutting device can also be used for high-precision machining processes.

[0022] Compared to the representation as shown in FIGS. 1 to 3, the retaining rib 34 with the metal-cutting machine tool 22 can also be located on the opposite side, i.e., on the right side 18 in the machining direction. Alternatively, several holders 10 (not shown) with metal-cutting tools 22 can be located in the horizontal plane next to one another. Two cutting devices located adjacent to one another can also have the metal-cutting tool 22 once on the left and adjacently opposite on the right side of the metal-cutting tool 22. It is also possible in a vertical plane to move several of the cutting devices on top of one another in the machining configuration if the machining processes should dictate this.

[0023] The following embodiments are now specified only to the extent that they differ significantly from the preceding embodiment. The same reference numerals are used for identical parts, the previous statements in this respect also applying accordingly to the other embodiments.

[0024] The second embodiment as shown in FIGS. 4, 5, and 6 differs from the first embodiment in that the front face 28 with its camber 32 now extends over the entire height of the clamping head 20. In the second embodiment of the cutting device the clamping gap 40 is penetrated by an actuation opening 48 which can be spread by way of an actuating key (not shown) with a polygonal actuation cross section in order in this way to enlarge the clamping gap 40 and to widen the receptacle 24 such that the metal-cutting tool 22 is released for a replacement process. With the continued turning of the polygonal key, the actuation opening 48 in turn closes; the clamping gap 40 is narrowed, and accordingly the receptacle 24 for the metal-cutting tool 22 which is omitted in FIG. 4. Here the camber 32 in the clamping head 20 also recedes such that the workpiece 30 with its maximum machining diameter can fit into the released parts of the clamping head 20. Furthermore, the camber 32 and accordingly the retaining rib 34 are stiffened by way of the obliquely running support surface 46 (compare FIG. 5).

[0025] In the third embodiment as shown in FIGS. 6 and 7, the camber 32 of the front face 28 is present only in the area of the height of the receptacle 24, and otherwise the front face 28, as shown especially by FIG. 7, is provided with a run-off bevel 50 which draws back towards the bottom 14. The run-off bevel 50 in question likewise ensures that unintended collisions between the cutting device and the workpiece 30 cannot occur. Since the camber 32 is designed with its curvature however only partially through the front face 28, it is not possible with the machining cutting edge 26, as in the above described approaches, to advance as far as the middle of the workpiece 30, i.e., up to its axis of rotation. The third embodiment is therefore intended for special machining situations, in which a cut-off process is not absolutely specified, for example. But it is still possible in such an instance, without colliding with the workpiece 30, to penetrate far into the workpiece 30 with the metal-cutting tool 22 for producing a narrow machining groove.

[0026] To prevent collisions, it can however be provided in any case that the distance between the cambered front face 28 of the clamping head 20 and the machining cutting edge 26 of the metal-cutting tool 22 is slightly larger than the largest possible diameter of the rotating workpiece 30 which is intended for machining with this metal-cutting tool 22. With the cutting device claimed for the invention, high-precision machining can be done and great penetration depths can be implemented on the workpiece without first having to form the corresponding clear spaces in the workpiece 30 by cutting, as in the prior art, so that the clamping head 20 can follow the machining direction of the metal-cutting tool 22 into the workpiece 30. 

1. A cutting device with a holder (10) which is provided on the clamping head (20) for holding a metal-cutting tool (22) with a jaw-like receptacle (24) that is located on one longitudinal side (16) of a clamping head (20), with a front face (28) which runs transversely to its longitudinal side (16) facing the workpiece (30) which rotates during metal-cutting machining, characterized in that the front face (28) at least in the area where it leads into the receptacle (24) is provided with a camber (32) whose curvature corresponds to the curvature of the workpiece (30) with the largest diameter for which the cutting device is intended.
 2. The cutting device as claimed in claim 1, wherein the receptacle (24) is part of the retaining rib (34) which projects as an integral component of the clamping head (20) from the latter, and wherein the camber (32) of the front face (28) extends from the area of the receptacle (24) to the bottom (14) of the clamping head (20).
 3. The cutting device as claimed in claim 1 or 2, wherein the camber (32) of the front face (28) on the top (12) of the clamping head (20) undergoes transition into an obliquely running flattened area (36) which is penetrated by a setscrew (38) which changes the clear cross section of the clamping gap (40) which passes at least through the clamping head (20) and which leads into the receptacle (24).
 4. The cutting device as claimed in one of claims 1 to 3, wherein the camber (32) of the front face (28) extends over the entire height of the clamping head (20) with its assigned curvature.
 5. The cutting device as claimed in one of claims 1 to 4, wherein the distance between the cambered front face (28) of the clamping head (20) and the machining cutting edge (26) of the metal-cutting tool (22) is slightly larger than the largest possible diameter of the rotating workpiece (30) which is designed for machining with this metal-cutting tool (22).
 6. The cutting device as claimed in one of claims 4 or 5, wherein the clamping gap (40) leads out from the clamping head (20) into parts of the holder (10) and wherein in the area of the clamping head (20) the clamping gap (40) is penetrated by an actuation opening (48) which enlarges the clamping gap (40) and the receptacle (24) for releasing the metal-cutting tool (22) with a spreading capacity by way of an actuating key.
 7. The cutting device as claimed in claim 3, wherein the clamping gap (40) in the area of its longitudinal side (18) facing away from the receptacle (24) is penetrated at least partially by a bearing block site (42).
 8. The cutting device as claimed in one of claims 1 to 7, wherein the cambered front face (28) on the bottom (14) of the clamping head (20) undergoes transition into a support surface (46) which extends obliquely to the feed direction of the metal-cutting tool (22) from the receptacle (24) in the direction of the clamping head (20).
 9. The cutting device as claimed in one of claims 1 to 8, wherein the metal-cutting tool (22) is provided with two effective cutting edges (26) which are diametrically opposite one another.
 10. The cutting device as claimed in one of claims 1 to 9, wherein the metal cutting tool (22) can be fixed selectively on one of the two longitudinal sides (16, 18) of the clamping head (20). 